Apparatus for the automatic separation of a negative sheet and a photosensitive sheet from the stack of them on a photocopier

ABSTRACT

The automatic separator for the separation of a sheet stack consisting of a negative sheet and a photosensitive sheet into its constituent sheets after exposure in a photocopier comprises a continuously rotating feed roll and a reversibly rotatable separator roll cooperating therewith to momentarily drive the negative sheet and the photosensitive sheet in opposite directions. A pressure roller also cooperates with the feed roll and is arranged to keep the remaining sheet under pressure along a predetermined length of the peripheral surface of said feed roll and in cooperation with said reversibly rotatable separator roll. The direction of rotation of the pressure roller is dependent upon the direction of movement of the sheet of the stacks in contact therewith.

United States Patent Taltahaski 1 51 Aug.15,1972

[72] Inventor: Isao Takahaski, 5-2-12, Sendagi,

Bunkyo-ky, Tokyo, Japan 22 Filed: Oct. 20, 1970 21 App]. No.: 82,381

[30] Foreign Application Priority Data I Dec. 16, 1969 Japan ..44/118966 52 11.s.c1 ..271/64, 271/18 51 1111.01. ..B65l129/64 [58] Field 011 Search ..271/18, 64, 54

[56] References Cited UNITED STATES PATENTS 3,537,703 11/1970 Blow....l ..27l/l8 3,297,317 1/1967 Stievenart ..271/64 584,073 6/1897 Dexter ..271/57 Primary Examiner-Evon C. Blunk Assistant Examiner-Bruce H. Stoner, Jr.

Attorney-Sughrue, Rothwell, Mion, Zinn & Macpeak ABSCT The automatic separator for the separation of a sheet stack consisting of a negative sheet and a photosensitive sheet into its constituent sheets after exposure in a photocopier comprises a continuously rotating feed roll and a reversibly rotatable separator roll cooperating therewith to momentarily drive the negative sheet and the photosensitive sheet in opposite directions. A pressure roller also cooperates with the feed roll and is arranged to keep the remaining sheet under pressure along a predetermined length of the peripheral surface of said feed roll and in cooperation with said reversibly rotatable separator roll. The direction of rotation of the pressure roller is dependent upon the direction of movement of the sheet of the stacks in contact therewith.

3 Claims, 20 Drawing Figures PATENTEDM'B 5 m saw u or 4 FIG.

APPARATUS FOR THE AUTOMATIC SEPTION OF A NEGATIVE S *l: I T AND A PHQTOSENSITIVE SHEET FROM 1 STACK OF THEM ON A PHOTOCOPIER This invention relates to improvements in and relating to an automatic separator mechanism for the separation of a sheet stack consisting of a negative sheet and a photosensitive sheet into its constituents upon their being delivered from the exposure section of a photocopier and during passage of the stack to the developing section of the copier.

It is already known to use for this purpose such a separator mechanism comprising a reversibly driven roll cooperating with a continuously rotating roll. The sheet stack upon being delivered from the exposure section is fed to the separator mechanism wherein the first or the reversibly driven roll is rotated to feed the stack in the advancing direction to the developing section and after a short delivery upon being caught by the cooperating rolls, the first roll is rotated in the reverse direction for carrying out the desired separation.

According to our experience, the desired sheet separation can be carried out in an efficient way so far as the width of the sheet stack amounts to 300 mm or less. Difficulties in the separation are frequently encountered, however, with use of longer separating rolls than above specified, on account of inevitable inferior workmanship in the roundness and the straightness of these rolls.

It is therefore the main object of the present invention to provide a sheet separator mechanism of the above kind which is capable of performing the desired sheet separation irrespective of unavoidable inferior workmanship in the roll fabrication.

Another object is to provide a separator mechanism of the above kind, capable of providing a sufficient feed friction to selected one sheet of the sheet stack necessary for feeding it in its regular advancing direction at the critical moment of the sheet separating operation in the separator mechanism.

According to the present invention, the thinnest negative sheet, for instance, in the order of 0.08 mm thick, may be separated without any trouble from the exposed sheet stack comprising a thin photosensitive sheet, for instance, in the order of 0.04 mm thick. A heavier combination of a thick negative made of acetate film in the order of 0.1 1 mm thick with a thick photosensitive sheet, for instance, 0.1 1 mm thick, can be separated with ease, as ascertained by our practical experiments. There is no necessity of adjusting the roll gap in this case, even when the thinnest sheet stack and the heaviest sheet stack of the kind above referred to are treated successively.

These and further objects, features and advantages of the invention will become more apparent when reading the following detailed description of substantially two preferred embodiments of the invention shown in the accompanying drawings only by way of example.

In the drawings:

FIG. 1 is a perspective view of a roller assembly for separating an overlapped stack of a negative sheet and a photosensitive paper into its constituents from each other.

FIG. 2 is a front view of the roller assembly.

FIG. 3 is a top plan view thereof.

FIG. 4 is an end view thereof.

FIG. 5 is a part of the roller assembly, a part thereof being shown in its section.

FIG. 6, (I)( VI), illustrating several steps of the said sheet-separating process.

FIG. 7 is a perspective view of said roller assembly and several related constituent parts of a copier machine.

FIG. 8 is an end view substantially of the arrangement shown in FIG. 7.

FIGS. 9 and 10 are enlarged elevational views of a group of several intermeshing gears relating to the said sheet-separating operation.

FIG. 11 is a part of an electric circuit employed in the copier machine, including a microswitch and related several circuit parts.

FIG. 12 is a similar view to FIG. 1, illustrative of, however, a second embodiment of the sheet-separating roller assembly together with related several working parts of the photo-copier.

FIGS. 13 and 14 are respective enlarged elevational views of a group of mutually engaging gears similar to that shown in FIGS. 9 and 10.

FIG. 15 is an electric circuit employed in the second embodiment, including a photo-electrically operated switching means.

Referring now to the accompanying drawings, especially FIGS. 1-5, illustrative mainly of the sheetseparating roller assembly according to the first embodiment of the invention, it will be seen that the roller assembly comprises a pair of elongated separator rolls A" and C, the former having a larger diameter than the latter, and a series of freely rotatable rollers generally shown by a reference symbol B. Said separating rolls A and C are made of rubber, plastics or even metal and mounted rigidly on respective supporting shafts 10 and 11, respectively. Roller B is made of rubber, plastics or the like pliable material and rotatably mounted in a series group of separated roller elements on a common shaft 12. Each of said roller elements shown most clearly in FIG. 5 at 13 is prevented from occasional axial shift positively by a pair of positioning snap rings 15 which are rigidly, yet detachably mounted in respective circular grooves 14 formed on the shaft 12.

The sheet-separating roller arrangement employed in this invention is not limited to that so far shown and described, but, it can be said according to our practical experiments that the arrangement shown in FIGS. 1 3 is believed most effective.

The shafts 10-12 mounting the sheet-separating rolls and rollers A, B and C pass through the side walls 16a and 16b of a framework 16 of the photocopier, as most clearly seen from FIG. 2, of which the first shaft 10 is rotatably supported at its one end in a stationary bearing 18 which is attached in turn rigidly to an eccentric disc 17 rotatably mounted on the side wall 16a. This eccentric disc 17 is formed on its periphery with serrations or recesses 19, one of the latter being kept in engagement with a stationary stop member 21 which is fixedly attached onto the outer surface of the said frame wall 16a by means of set screws 20. By proper selection of the engagement of one of the recesses 19 with said stop member 21, the distance between the rolls A and C can be adjusted to a certain degree depending upon the eccentricity of disc 17 relative to the shaft 10.

A bearing plate 22, made preferably of a rigid plastic material such as polyamide resin is rigidly attached onto the outer surface of the frame wall 16a by means of a plurality of set screws 23, an elongated opening 220 being formed through said bearing plate for rotatably receiving one end of said shaft 12 which is fitted rigidly with a stop flange 74 for the prevention of occasional disengagement of the shaft end from the bearing opening 220 which provides an adjustability in the bearing position of said shaft 12.

Normally, a spring hook 25 fixedly mounted at its one end portion by means of set screws 24 on the frame wall 116a is kept by its curved tip end in resilient contact with the shaft end, thereby the rollers B being kept in pressure engagement with the mating roll The shaft I1 is rotatably mounted in a stationary bearing 26 which is mounted rigidly on the frame wall 160.

Although not specifically described, the shafts -12 are supported on the other frame wall 16b in the similar way as referred to above, as seen especially from FIG. 2 and 3.

Sheet-separating rolls A" and C" are relatively positioned so as normally to have a small roll gap, on the order of 0.05 mm. But, when these rolls are covered with a plastic sponge, they can be kept always in an intimately contacting relationship. Normally, these rolls A and C are separately and forcibly driven. Since the rollers B" are kept in pressure contact with the roll A, and the shaft 12 for the roller series B" is not externally driven the roller elements 13 are rotated by receiving motion from the contacting roll A."

A series of separated sheet guide plate 76 are fixedly mounted on an elongated stationary shaft 75 which is rigidly mounted in turn at its both ends in the frame walls 160 and 16b. These guides 76 serve for properly guiding a stack of the negative sheet and the photosensitive paper sheet, not shown, so as to pass through between the roll A and the roller group B," instead of the similar gap formed between the rollers B" and the remaining roll Each of these sheet guides 76 is kept in slidable engagement with a ring groove 77 formed on the roll C and positioned in the idle space formed between two neighboring rollers B.

The operation of the sheet-separating roller arrangement so far shown and described may best be understood by reference to FIG. 6, (I) VI).

As was briefly described hereinbefore, both rolls *A and C" can be positioned relative to each other so as to have a small idle gap, or alternatively, they may be arranged so as to be in pressurized and rolling contact with each other. In the following, the former case will be adopted for more clear description of the apparatus.

An overlapped stack of a negative sheet 0 and a sensitive sheet 8" is fed-in along a stationary guide plate 27 to the roller arrangement from below in the manner as shown at (I) in FIG. 6. In this case, the top or leading end of the sheet stack will be brought into contact with a point D on the peripheral surface of the first roll A" which point is defined by an extension of the guide plate crossing with the peripheral surface of said roll. This point D is situated on the roll surface A" at a slightly leading position from a point E which is defined by a crossing point ofa line connecting the centers of both rolls A" and C with the peripheral surface of the latter roll. The central angle including the both points D" and E" relative to the outer surface of the first roll A is denoted in FIG. 6 at (I) by 0" which is advantageously 20 or less as ascertained by our practical experiments. The rotational directions of the rolls A" and C" and the rollers B are shown by respective small arrows.

Since the feed speed of the sheet stack is selected slightly higher than the peripheral speeds of the rolls A" and C, there will appear a slight slack as at L," in the travel passage of the sheet stack directly after being caught by and between the rolls A" and B, as shown at (II) in FIG. 6.

As a next step shown at (III) in FIG. 6, the sheet stack will invade forcibly through the engaging point between roll A" and rollers B upon urging the latter upwards against the action of pressure springs 25. For a short time, these rollers 8" are rotated as shown at (III) by contact with the sheet stack which has a certain rigidity serving for this driving purpose assisted by the constantly rotating roll A.

Directly after the leading end of the sheet stack has passed the engaging point between the roll A" and rollers B, the separator roll C" is reversed in its rotational direction as shown at (IV) in FIG. 6, as will be more fully described hereinafter. Briefly, the leading edge of the sheet stack is sensed by a feeler and an electric switching means such as microswitch or photoelectric switching element is actuated for delivery of an electrical signal for controlling the mechanical drive means for the separator roll C to be described.

In fact, however, the roll C" is kept stationary in advance of the initiation of the said reversed drive of the roll C," with the rollers B being also kept provisionally in a stationary position, while the remaining roll A only is driven continuously in the same rotational direction as before. It will be seen that at this stage, the sensitive sheet 5" is kept stationary and forms a slackened part L as shown at (IV) in FIG. 6.

Upon initiation of the reversed drive of the separator roll C, said slack L will be intensified and enlarged as shown at L in FIG. 6 (V) and with further continuation of the reverse rotation of roll C, the leading part of sheet 5" will be separated from contact with the negative sheet 0 so as to travel along a specific discharge route attributed thereto, whereupon the roll C" is returned to its regular rotating direction. At this stage, the rollers B rotate in pressure and rolling contact with the negative sheet 0. Upon separation of this sheet from contact with the rollers B" and the roll A," the latter is brought resiliently under the action of the urging spring 25 into its initial position, so as to nullify the gap between the rollers B and the roll, with these again being brought into directly rolling contact.

Next, referring to FIGS. 7-11, an embodiment of a photocopier comprising the separator roll arrangement so far shown and described is shown.

In these figures, numerals 10, ll, l2, l3, 15, 16a, 27, and 76 and symbols A, B and C denote respective similar parts as before.

Numeral 28 denotes a microswitch which is mounted on one end of an elongated mounting bar 57. A drive gear 29 is fixedly mounted on a shaft 56 and a first intermediate gear 30 meshes with the drive gear 29 and a driven gear 31 which is fixedly mounted on the shaft 11 already referred to. Numeral 33 denotes a change-off lever which carries thereon rotatably a second intermediate gear 32 in addition to said first intermediate gear 30 which is also rotatably mounted. By manipulating this change-off lever 33, the second intermediate gear, in place of the first intermediate gear, can be brought into meshing with said driven gear 31, as will be more fully described hereinafter.

A tension spring 34 is tensioned between a stationary pin 35 which is fixedly mounted on the frame wall 16a although not shown, and the change-off lever 33, the latter having a follower roller 37 at its tip end.

Numeral 36 denotes a solenoid coil which is mounted on the same frame wall 16a, although not shown, and provided with a plunger 42. A cam 38 is loosely mounted on a rotatable shaft 52, said follower roller 37 being kept in pressure engagement with the periphery of this cam under the action of tension spring 34. The configuration of the cam 38 is most clearly shown in FIGS. 9 and 10.

A ratchet wheel 39 is mounted again loosely on the shaft 52 in an overlapped manner to the cam 38, a pawl 40 being arranged to engage with the teeth on the ratchet 39. This pawl 40 is pivotably mounted at its intermediate point 40a between its end extremities on the cam 38. The outer end of pawl 40 is kept in pressure engagement with a spring strip 45 which is mounted fixedly at its root end on the cam 38 for resiliently urging the pawl 40 in its engaging direction.

A lever 41 is pivotably connected at its intermediate point at 43 with the inner end of the plunger 42 of the solenoid 36, while the outer end of said lever 41 is pivotably mounted at 44 on the stationary side wall 16a, although the mounting structure has been omitted from the drawing for simplicity. The inner or operating end of the lever 41 extends inwardly, as shown, to a substantial distance so as to mechanically actuate the pawl 40 for control of the engagement with and the disengagement from the ratchet teeth at 39.

A pair of feed rolls 46 and 47 are fixedly mounted on their respective parallel shafts 48 and 49 which are rotatably mounted at their ends on stationary side walls 16a and 16b, although the mounting means have been omitted from the drawing only for simplicity. However, it should be mentioned that in practice the shaft 49 has its reduced part 49a (FIG. 7) rotatably supported on the side wall 16a, carrying fixedly a drive gear 50 and mechanically connected to a prime mover, preferably an electric motor, although not shown. A driven gear 51 is fixedly mounted on the shaft 52 and an endless rack belt 53 is suspended between the gears 50 and 51. As may be seen from the foregoing, when the pawl 40 is brought into engagement, as will be more fully described hereinafter, cam 38 and ratchet 39 are mechanically united together for performing a unitary motion.

A drive gear 54 is fixedly mounted on the shaft part 490 and a driven gear 55 is fixedly mounted on the shaft 56, these gears 54 and 55 being operatively connected with each other by means of a toothed endless belt 66.

A feeler 59 made of a strip spring is positioned in close proximity to the feeding roll pair 46-47 so as to sense physically with its tip end the leading edge of travelling sheet stack along the inside curved surface of a guide plate 60. The root end of the spring feeler 59 is fixed to a rotatable bar 58 which passes through the microswitch 28 for on-off control thereof. Although the mounting bar 57 is shown partially in FIG. 7, it is rigidly supported at its both ends on the side walls 16a and 16b, respectively. These side walls mount again rigidly the both ends of the guide plate 60, although not shown. In FIG. 7, a transparent exposure drum 6! is also shown, but only partially. As conventionally done, this drum is rotatably supported at its each end by means of a plurality of, preferably three, supporting rollers which are mounted on the side wall 16a or 16b, respectively, although not shown. Within the interior space of the drum 61, there is fixedly provided a plurality of elongated illuminating lamps -82. In addition, a plurality of driving belts 63 are provided as shown, for rotating the exposure drum. An elongated guide roll 62 is mounted rigidly on a shaft 83 which is mounted rotatably at its both ends on the side walls 160 and 16b, although not shown. Similar guide rolls 84-87 are similarly provided and rotatably mounted.

A similar roll 88 is also provided so as to cooperate through the belts 63 with guide roll 87 so as to receive the sheet stack for the delivery thereof into the interior of the copier, as will be more fully described hereinafter (FIG. 8).

A further similar roll 89 is provided so as to cooperate through belts 63 with guide roll 84 for delivery of the sensitive sheet S separated from the sheet stack 0-5, as will be more fully described with reference to FIG. 8 hereinafter.

Several feed roll pairs 90;91, 92;93 and 94;95 are provided for further delivery of the separated sensitive sheet S through the developer section including a developer vat 96 in which a body of a conventional developing liquor 97 is contained and one of the feed roll 93 is partially dipped therein for serving as liquid supplier.

Turning back to FIG. 7, numeral 64 denotes an elongated shaft rotatably mounted at its both ends on side walls 160 and 16b, although not shown, a plurality of guide discs shown by a common reference numeral 65 being fixedly mounted one after another on the shaft at regular intervals, so as to act as a guide for directing the separated sensitive sheet 5" towards guide roll 62 for being carried by on the belts 63.

In FIGS. 7 and 8, scraper 67 made preferably of a thin metal sheet is fixedly mounted on the inner side edge of the curved guide plate 60 for separating the sheet stack O-S from the carrier surface of the exposure drum 61, as will be more fully described hereinafter.

An electric circuit adapted for control of the motion of the reversible roll C is shown in FIG. 11.

In FIG. 11, numerals 98 and 99 denote input terminals which are connected to an ac. current source, not shown. 68 denotes a condenser; 28 said microswitch; 36 said solenoid coil; 69 a relay coil; 69a a normally closed relay contact controlled by the latter; 100 a resistor; 101 a rectifying diode; and 102 a resistor. These circuit elements are connected as shown.

The operation of the copier comprising the sheet separator embodying the principles of the invention is as follows:

At first, the drive motor, not shown, is started so as to bring the belts 63 and gears 50, 51, 54 and 55 and shafts 10, 48 and 49 into operation.

Next, the stack of a negative sheet and a sensitive sheet S is fed by hands between the rollers 87 and 88 and onto the right hand ends of the belts 63 in FIG. 8. These belts are driven continuously at a predetermined travelling speed, since either one of rollers 62 and 87 is mechanically connected to the shaft 49 or 56, although not shown. The drum 61 is thus kept in rotation. The stack is carried by these travelling carrier belts 63 around the exposure drum 61, thus the sensitive sheet 8" being exposed through the negative sheet 0" to light beams radiating from the lamps 89452. Upon contact of the exposed sheet stack with the scraper 67, it is separated from contact with the outer peripheral surface of the rotating drum and then guided by the first or curved stationary guide plate 60 so as to travel along the inside surface thereof, when seen in FIG. 8. Then, the leading edge of the stack is brought into contact with the feeler 59, thus microswitch 28 is transferred from its full line to its dotted line position shown in FIG. 11.

With the microswitch 28 kept in its full line position, the a.c. current is rectified by diode 101 and charged in condenser 68. Solenoid 36 is also energized on account of the closed state of relay contact 69a.

With the switch 28 transferred into its dotted position in FIG. 11, condenser 68 will start to discharge, thereby the relay coil 69 being energized to open provisionally its contact 69a and thus de-energize solenoid coil 36.

With the solenoid 36 energized normally in the above described way, its plunger 42 is kept in its depressed position shown in FIG. 7, so as to keep the pawl 40 in its disengaged position from ratchet 39. However, when microswitch 28 is transferred from its normal position in FIG. 11 to the dotted line position in the above-mentioned way, the condenser 68 will start to discharge, provisionally so to speak, so that relay coil 69 is energized and its contact 69a is opened, so as to de-energize the solenoid 36. In this way the plunger 42 is brought into its upper position so that lever 41 is turned a small angle in counter clockwise direction in FIG. 7, thus pawl 40 is brought into engagement with ratchet 39 under the influence of the urging spring 45. In this way cam plate 38 and ratchet 39 are brought into a unitary combination. Therefore, the cam plate 38 will initiate its rotation from the position shown in FIG. 9 to that shown in FIG. 10.

The relative phase relationship of the positions of the cam 38 is so selected that when the sheet stack has been advanced from the position where the stack contacted the feeler 59 to the position where it is caught by the roll A and rollers 8" and a reverse rotation of roll C" is necessary as shown in the operating stage in FIG. 6 at IV, the plunger 42 is actuated upwards in FIG. 7, as was referred to above.

In the position shown in FIG. 9, motion is transmitted from drive gear 29 through belt 66 (which has been omitted from FIG. 9 on account of space limitation) and intermediate pinion 30 to the driven gear 31. Thus, the gear 31 and the reversible roll C" are rotated in counter clockwise direction in FIG. 9 which means the regular advancing feeding direction of roll C.

In the position shown in FIG. 10, however, the second intermediate pinion 32 is incorporated into the gear train, thus the driven gear 31 and the reversible roll C" are rotated in clockwise direction in FIG. 10, which means the reversed rotational direction of the roll C" adapted for performing the aforementioned sheet separation. The discharging period of the condenser 68 is so selected that it will terminate upon a complete revolution of the cam 38.

The provision of the roller series B plays an important role for the desired positive separation of the sheet 5" from the remaining sheet 0" During whole progress of the sheet separation, the sheet 0" is kept in pressure engagement with the outer peripheral surface of the continuously rotating roll A along a substantial peripheral distance extending from the first contact point between roll pair A" and C to the second contact point between roll A" and rollers B," therefore, a feared accompanying action of the sheet 0" by the sheet S which is now being subjected to the reversed motion relative to the continuously advancing sheet and kept in a direct and frictionally sliding contact with the latter can be effectively and positively prevented.

Therefore, the negative sheet O," even it be a possible thinnest one, is very difficult to draw backwards relative to its travelling passage around the feed roll A, as met during the separating process by the possible accompanying action provided by the sensitive sheet S as it is being withdrawn in the reversingly travelling stages as at (IV) and (V) shown in FIG. 6. Since the friction acting between the both sheets 5" and O is substantially smaller than that acting between the negative sheet 0" and the feed roll surface at A," as ascertained by various and numerous experiments, the desired separating operation is absolutely guaranteed by adopting the principles of the invention.

It will be easily appreciated that no further revolution beyond a complete revolution of the cam 38 is brought about upon each actuation of the feeler 59 by contact of the leading edge of the sheet stack. Upon completion of the sheet separation in the aforementioned manner and upon termination of the condenser discharge at 68, the relay coil 69 is de-energized again so that relay contact 69a is closed again. Thus, the roll C is brought into its regular moving conditions, and so on.

The leading edge'of the separated sensitive sheet is at first brought into a provisional contact with the constantly rotating discs 65, thus being directed towards the uppermost travelling zone of the belt series 63, as hinted by a dotted line denoted S in FIG. 8. This separated sheet is then fed successively through guide roll pairs 84,89; 90, 91; 92, 93; and 94, 95 for being subjected to a developing action and then taken out. The developing is carried out during travel through the roll pair 92, 93, the lower roll 93 of which acts as a developer roll, taking up a developing liquor from the vat 96, 97 for wetting the already exposed sheet S as conventionally.

On the contrary, the negative sheet 0 will further advance along the destined travel route for being taken out of the copier, as conventionally.

In FIGS. 12-15, a modified embodiment from the foregoing is shown only in a simplified way.

In this modification, the microswitch 28 has been replaced by a pair of photoelectric elements 70 and 71, the light beam passage for these elements being positioned in close proximity to the delivery nip line between the feed roll A" and pressure rollers B" as seen most clearly from FIG. 12.

Further, in this modified arrangement, the plunger 42' of solenoid 36' which correspond those denoted 42 and 36 in the foregoing, respectively, is linkedly connected directly with the lower end of the change-off lever 33 carrying the intermediate pinions 30 and 32. In FIG. 15, said photoelectric elements 70 and 71 are shown only in a functional way for easy comparison with the microswitch 28 employed in the foregoing embodiment.

In the present embodiment, the shaft 10 carries a gear 72 fixedly mounted thereon and meshing with a gear element 29". A double gear 73 is rotatably mounted through its shaft 56 on the change-off lever 33 and formed with two parallel gear elements 29' and 29". The former gear element 29' is kept in meshing with the intermediate pinion 30, which meshes in turn with the driven gear 31 as before.

The operation of the modified arrangement will now be described hereinbelow:

When the leading edge of the sheet stack comes to the point crossing an imaginary line 103 joining the two photoelectric elements 70 and 71, the normally interrupted photoelectric switch 70, 71 is transferred from its full line position toits dotted line position shown in FIG. 15, thus the solenoid 26' is energized.

With energization of solenoid 36', the plunger 42 is attracted against a return spring 34' (FIG. 12 and 13) which is tensioned between the inside end of the plunger and a stationary post 35' mounted on the side wall 16a although not shown, thus the gear transmission relationship is shifted from the position shown in FIG. 13 to that shown in FIG. 14.

Since the transmission relationship shown in these FIGS. 13 and 14 correspond to those shown in FIGS. 9 and 10, respectively. No further description on the analysis of the power transmission through the gearing for initiating the reverse drive of the roll C and for recovery of the regular driving mode of the latter.

The electric circuit employed in the present modified arrangement and comprising the photoelectric switch 70, 71 and the solenoid 36 is shown in FIG. 15 in a highly simplified way. The terminals shown at 98' and 99 correspond respectively to those shown at 98 and 99 in FIG. 11.

Guide plates 27 and 60 are also provided in the present modified arrangement for the same purpose as before although not shown only for simplicity. Although not shown, the former guide plate 27 is also fixed at its both ends on the both side walls 16a and 16b, respectively, throughout all the embodiments so far shown and described.

Upon completion of the sheet separation and when the trailing edge of the remaining advancing sheet 0 has completely moved from the position corresponding to the said imaginary line 103, the switch 70, 71 will be transferred from its dotted line back to its full line position in FIG. 15, thus the roll C being brought into its regularly and advancingly rotating position, as was referred to hereinbefore in the foregoing embodiment, and so on.

Since the shaft 12 mounting the pressure r'oller series B is pivotably mounted under pressure exerted by the 25 which feature is employed also in the modified arrangement shown in FIG. 12-15, a sufiicient pressure is given to the remaining sheet 0" throughout the whole sheet-separating procedure, yet allowing the reverse feeding of the sensitive sheet 5" kept in sliding contact with the advancing sheet 0" during the separation process.

Under occasions, the sensitive sheet S and the negative sheet 0" can be exchanged in their position to each other in every embodiment.

What is claimed is:

l. A sheet separator for use in a photocopier for the separation of a sheet stack consisting of a negative sheet and a photosensitive sheet, into its constituent sheets, comprising a frame, a continuously rotatable feed roll mounted in said frame, and a reversible rotatable separator roll mounted in said frame adjacent said feed roll, the improvement comprises a series of pressure rollers, a common shaft for mounting said pressure rollers swingably on said frame, spring means biasing said common shaft in the direction for bringing said pressure rollers towards contact with said feed roll, whereby one constituent of said stack is always kept in pressure contact with said feed roll for a predetermined distance along the periphery of said feed roll when the stack is passing through the nip line between said feed roll and said separator roll, said predetermined distance being defined as the distance between said nip line and the contact line between said pressure rollers and said feed roll, drive means for rotating said separator roll in a direction opposite to the direction of rota tion of said feed roll to feed said stack between said feed roll and said separator roll and said pressure rollers, said drive means including a first unidirectionally driven gear, a separator roll gear mounted for rotation with said separator roll, plate means pivotally mounted about the axis of said unidirectionally driven gear, a pair of idle gears mounted on said plate means, disposed in mesh with each other and located intermediate said driven gear and said separator roll gear, means for oscillating said plate means between a first position where one of said idle gears is disposed in mesh with said driven gear and said separator roll gear and the other idle gear is free to rotate said separator roll in the direction opposite the feed roll and a second position where said one idle gear is in mesh with said driven gear and said other idle gear is in mesh with said separator roll gear to rotate said separator roll in the same direction as the feed roll, sensing means for detecting the leading edge of said stack, and control means responsive to said sensing means for moving said oscillating means from said first position to said second position to reverse the direction of rotation of said separator roll.

2. A sheet separator as set forth in claim 1, wherein said sensing means comprises a micro switch positioned along the path of travel of said sheet stack prior to said feed roll and said separator roll, said micro switch having a feeler for detecting the leading edge of said stack, said micro switch being operatively connected to said control means, said control means further including timing means for initiating movement of said oscillating means from said first position to said second position tect the leading edge of said stack, said photoelectric detector being operatively connected to said control means to actuate said control means to actuate said control means to move said oscillating means from said first position to said second position upon interruption of a light beam from said light source.

UNITED STATES PATENT oFFlcE CERTIFICATE OF CORRECTION Patent No. 3, 684, 278 Dated August 15, 1972 Inventor(s) lsao Takahashi It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In The Heading:

The name of the Assignee was omitted. Should read:

--Assignee: BUNSHODO CO. LTD. Tokyo, Japan-- Signed and sealed this 13th day of March 1973 (SEAL) Attest: 7. no

ROBERT GOTTSCHALK EDWARD M FLETCHER, JR

Commissioner of Patents Attesting Officer FORM Po-105O (10-69) USCOMM-DC 60376-P69 U.5. GOVERNMENT PRINTING OFFICE: I969 O366-334 

1. A sheet separator for use in a photocopier for the separation of a sheet stack consisting of a negative sheet and a photosensitive sheet, into its constituent sheets, comprising a frame, a continuously rotatable feed roll mounted in said frame, and a reversible rotatable separator roll mounted in said frame adjacent said feed roll, the improvement comprises a series of pressure rollers, a common shaft for mounting said pressure rollers swingably on said frame, spring means biasing said common shaft in the direction for bringing said pressure rollers towards contact with said feed roll, whereby one constituent of said stack is always kept in pressure contact with said feed roll for a predetermined distance along the periphery of said feed roll when the stack is passing through the nip line between said feed roll and said separator roll, said predetermined distance being defined as the distance between said nip line and the contact line between said pressure rollers and said feed roll, drive means for rotating said separator roll in a direction opposite to the direction of rotation of said feed roll to feed said stack between said feed roll and said separator roll and said pressure rollers, said drive means including a first unidirectionally driven gear, a separator roll gear mounted for rotation with said separator roll, plate means pivotally mounted about the axis of said unidirectionally driven gear, a pair of idle gears mounted on said plate means, disposed in mesh with each other and located intermediate said driven gear and said separator roll gear, means for oscillating said plate means between a first position where one of said idle gears is disposed in mesh with said driven gear and said separator roll gear and the other idle gear is free to rotate said separator roll in the direction opposite the feed roll and a second position where said one idle gear is in mesh with said driven gear and said other idle gear is in mesh with said separator roll gear to rotate said separator roll in the same direction as the feed roll, sensing means for detecting the leading edge of said stack, and control means responsive to said sensing means for moving said oscillating means from said first position to said second position to reverse the direction of rotation of said separator roll.
 2. A sheet separator as set forth in claim 1, wherein said sensing means comprises a micro switch positioned along the path of travel of said sheet stack prior to said feed roll and said separator roll, said micro switch having a feeler for detecting the leading edge of said stack, said micro switCh being operatively connected to said control means, said control means further including timing means for initiating movement of said oscillating means from said first position to said second position after a predetermined time period to allow passage of said sheet stack between said feed roll and said pressure rollers before moving said oscillating means from said first position to said second position.
 3. A sheet separator as set forth in claim 1, wherein said sensing means comprises a photoelectric cell and light transmission means positioned adjacent the line of contact of said feed roll and said pressure rollers to detect the leading edge of said stack, said photoelectric detector being operatively connected to said control means to actuate said control means to actuate said control means to move said oscillating means from said first position to said second position upon interruption of a light beam from said light source. 